Generalized hydrodynamics in strongly interacting 1D Bose gases

TL;DR

This paper experimentally validates generalized hydrodynamics (GHD) for strongly interacting 1D Bose gases, demonstrating its accuracy in predicting quasiparticle dynamics over multiple oscillations across various interaction strengths.

Contribution

It provides the first experimental confirmation of GHD's applicability to strongly interacting regimes in 1D Bose gases, extending its validated range beyond weak interactions.

Findings

GHD accurately predicts rapidity distributions over dozens of trap oscillations.

Experimental results agree with GHD theory across a wide range of interaction strengths.

Measurement of momentum distributions links quasiparticle evolution to interaction energy.

Abstract

The dynamics of strongly interacting many-body quantum systems are notoriously complex and difficult to simulate. A new theory, generalized hydrodynamics (GHD), promises to efficiently accomplish such simulations for nearly-integrable systems. It predicts the evolution of the distribution of rapidities, which are the momenta of the quasiparticles in integrable systems. GHD was recently tested experimentally for weakly interacting atoms, but its applicability to strongly interacting systems has not been experimentally established. Here we test GHD with bundles of one-dimensional (1D) Bose gases by performing large trap quenches in both the strong and intermediate coupling regimes. We measure the evolving distribution of rapidities, and find that theory and experiment agree well over dozens of trap oscillations, for average dimensionless coupling strengths that range from 0.3 to 9.3. By also measuring momentum distributions, we gain experimental access to the interaction energy and thus to how the quasiparticles themselves evolve. The accuracy of GHD demonstrated here confirms its wide applicability to the simulation of nearly-integrable quantum dynamical systems. Future experimental studies are needed to explore GHD in spin chains, as well as the crossover between GHD and regular hydrodynamics in the presence of stronger integrability breaking perturbations.